Stiff snoring implant

ABSTRACT

A method and apparatus for treating snoring of a patient includes providing an implant for altering a dynamic response of a soft palate of the patient to airflow past the soft palate. The implant is embedded in the soft palate to alter the dynamic response. For example, the implant has a mass, stiffness or dampening sufficient to alter the dynamic response following the implantation without substantially impairing a function of the soft palate to close a nasal passage of the patient during swallowing.

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/872,545 filed Jun. 1, 2001, which is a continuation of U.S.patent application Ser. No. 09/398,991 filed Sep. 17, 1999, now U.S.Pat. No. 6,250,307, which applications are incorporated herein byreference.

BACKGROUND

[0002] 1. Field of the Invention

[0003] This invention is directed to methods and apparatuses fortreating snoring.

[0004] 2. Description of the Prior Art

[0005] Snoring has received increased scientific and academic attention.One publication estimates that up to 20% of the adult population snoreshabitually. Huang, et al., “Biomechanics of Snoring”, Endeavour, p.96-100, Vol. 19, No. 3 (1995). Snoring can be a serious cause of maritaldiscord. In addition, snoring can present a serious health risk to thesnorer. In 10% of habitual snorers, collapse of the airway during sleepcan lead to obstructive sleep apnea syndrome. Id.

[0006] Notwithstanding numerous efforts to address snoring, effectivetreatment of snoring has been elusive. Such treatment may include mouthguards or other appliances worn by the snorer during sleep. However,patients find such appliances uncomfortable and frequently discontinueuse (presumably adding to marital stress).

[0007] Electrical stimulation of the soft palate has been suggested totreat snoring and obstructive sleep apnea. See, e.g., Schwartz, et al.,“Effects of electrical stimulation to the soft palate on snoring andobstructive sleep apnea”, J. Prosthetic Dentistry, pp. 273-281 (1996).Devices to apply such stimulation are described in U.S. Pat. Nos.5,284,161 and 5,792,067. Such devices are appliances requiring patientadherence to a regimen of use as well as subjecting the patient todiscomfort during sleep. Electrical stimulation to treat sleep apnea isdiscussed in Wiltfang, et al., “First results on daytime submandibularelectrostimulation of suprahyoidal muscles to prevent night-timehypopharyngeal collapse in obstructive sleep apnea syndrome”,International Journal of Oral & Maxillofacial Surgery, pp. 21-25 (1999).

[0008] Surgical treatments have been employed. One such treatment isuvulopalatopharyngoplasty. In this procedure, so-called laser ablationis used to remove about 2 cm of the trailing edge of the soft palatethereby reducing the soft palate's ability to flutter between the tongueand the pharyngeal wall of the throat. The procedure is frequentlyeffective to abate snoring but is painful and frequently results inundesirable side effects. Namely, removal of the soft palate trailingedge comprises the soft palate's ability to seal off nasal passagesduring swallowing and speech. In an estimated 25% ofuvulopalatopharyngoplasty patients, fluid escapes from the mouth intothe nose while drinking. Huang, et al., supra at 99.Uvulopalatopharyngoplasty (UPPP) is also described in Harries, et al.,“The Surgical treatment of snoring”, Journal of Laryngology and Otology,pp. 1105-1106 (1996) which describes removal of up to 1.5 cm of the softpalate. Assessment of snoring treatment is discussed in Cole, et al.,“Snoring: A review and a Reassessment”, Journal of Otolarvngology, pp.303-306 (1995).

[0009] Huang, et al., supra, describe the soft palate and palatalsnoring as an oscillating system which responds to airflow over the softpalate. Resulting flutter of the soft palate (rapidly opening andclosing air passages) is a dynamic response generating sounds associatedwith snoring. Huang, et al., propose an alternative touvulopalatopharyngoplasty. The proposal includes using a surgical laserto create scar tissue on the surface of the soft palate. The scar is toreduce flexibility of the soft palate to reduce palatal flutter. Huang,et al., report initial results of complete or near-complete reduction insnoring and reduced side effects.

[0010] Surgical procedures such as uvulopalatopharyngoplasty and thoseproposed by Huang, et al., continue to have problems. The area ofsurgical treatment (i.e., removal of palatal tissue or scarring ofpalatal tissue) may be more than is necessary to treat the patient'scondition. Surgical lasers are expensive. The proposed procedures arepainful with drawn out and uncomfortable healing periods. The procedureshave complications and side effects and variable efficacy (e.g., Huang,et al., report promising results in 75% of patients suggesting a fullquarter of patients are not effectively treated after painful surgery).The procedures may involve lasting discomfort. For example, scar tissueon the soft palate may present a continuing irritant to the patient.Importantly, the procedures are not reversible in the event they happento induce adverse side effects not justified by the benefits of thesurgery.

SUMMARY OF THE INVENTION

[0011] According to a preferred embodiment of the present invention,methods and apparatuses are disclosed for treating snoring of a patient.The invention includes providing an implant for altering a dynamicresponse of a soft palate of the patient to airflow past the softpalate. The implant is embedded in the soft palate to alter the dynamicresponse. For example, the implant has a mass, stiffness or dampeningsufficient to alter the dynamic response following the implantationwithout substantially impairing a function of the soft palate to close anasal passage of the patient during swallowing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a side sectional view of a portion of a human headshowing a soft palate in a relaxed state and in relation in adjacentanatomical features;

[0013]FIG. 2 is a portion of the view of FIG. 1 showing the soft palatein a flexed state;

[0014]FIG. 3 is a front view of an interior of the mouth shown in FIG. 1and showing an area to be ablated according to a first prior artsurgical procedure;

[0015]FIG. 4 is the view of FIG. 3 and showing an area to be scarredaccording to a second prior art surgical procedure;

[0016]FIG. 5 is a schematic representation of a spring-mass system modelof the soft palate;

[0017]FIG. 6 is the view of FIG. 1 with the soft palate containing animplant according to a first embodiment of the present invention;

[0018]FIG. 7 is the view of FIG. 3 showing the embodiment of FIG. 6;

[0019]FIG. 8 is a cross-sectional view of the implant of FIG. 6;

[0020]FIG. 9 is a first modification of the implant of FIG. 8 having atissue in-growth layer;

[0021]FIG. 10 is a second modification of the implant of FIG. 8 having asmooth outer layer;

[0022]FIG. 11 is the view of FIG. 6 with the soft palate containing animplant according to a second embodiment of the present invention;

[0023]FIG. 12 is the view of FIG. 7 showing the embodiment of FIG. 11;

[0024]FIG. 13 is a perspective view of the implant of FIG. 11;

[0025]FIG. 14 is a cross-sectional view of the implant of FIG. 13;

[0026]FIG. 15 is a view of the implant of FIG. 14 with the implantpre-formed to assume the shape of a soft palate in a relaxed state;

[0027]FIG. 16 is the view of FIG. 14 with the implant constructed tohave greater flexion in a downward direction;

[0028]FIG. 17 is an exploded perspective view of first modification ofthe implant of FIG. 13;

[0029]FIG. 18 is a perspective view of a modification of a housing ofthe embodiment of FIG. 17;

[0030]FIG. 19 is a side section view of a second modification of theimplant of FIG. 13;

[0031]FIG. 20 is a cross-sectional view of an implant that is anotherembodiment of the present invention, the implant is shown in a flattenedorientation;

[0032]FIG. 21 is a cross-sectional view of the implant of FIG. 20 in anexpanded orientation;

[0033]FIG. 22 shows the implant of FIG. 20 in the flattened orientationand implanted in the soft palate; and

[0034]FIG. 23 shows the implant in FIG. 21 in the expanded orientationand implanted in the soft palate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] For ease of understanding the present invention, the dynamics ofsnoring are explained with reference to FIGS. 1-4. The hard palate HPoverlies the tongue T and forms the roof of the mouth M. The hard palateHP includes a bone support B and does not materially deform duringbreathing. The soft palate SP is soft and is made up of mucous membrane,fibrous and muscle tissue extending rearward from the hard palate HP. Aleading end LE of the soft palate SP is anchored to the trailing end ofthe hard palate HP. A trailing end TE of the soft palate SP isunattached. Since the soft palate SP is not structurally supported bybone or hard cartilage, the soft palate SP droops down from the plane ofthe hard palate HP in an arcuate geometry of repose.

[0036] The pharyngeal airway passes air from the mouth M and the nasalpassages N into the trachea TR. The portion of the pharyngeal airwaydefined between opposing surfaces of the upper surface of the softpalate SP and the wall of the throat is the nasopharynx NP.

[0037] During normal breathing, the soft palate SP is in the relaxedstate shown in FIG. 1 with the nasopharynx NP unobstructed and with airfree to flow into the trachea TR from both the mouth M and the nostrilsN.

[0038] During swallowing, the soft palate SP flexes and extends (asshown in FIG. 2) to close the nasopharynx NP thereby preventing fluidflow from the mouth M to the nasal passages N. Simultaneously, theepiglottis EP closes the trachea TR so that food and drink pass onlyinto the esophagus ES and not the trachea TR. The soft palate SP is avalve to prevent regurgitation of food into the nose N. The soft palateSP also regulates airflow through the nose N while talking. Since thesoft palate SP performs such important functions, prior art techniquesfor surgically altering the soft palate SP can compromise thesefunctions.

[0039] The majority of snoring is caused by the soft palate SP flappingback and forth. If breathing is solely through the nose N with the mouthclosed, the trailing edge TE of the soft palate SP is sucked into thenasopharyngeal space NP obstructing the airway and subsequently fallsopening the airway in a repeating cycle. When the mouth is open, airflows over the upper and lower surfaces of the soft palate SP causingthe soft palate SP to flap up and down alternating in obstructing theoral and nasal passageways M, N. The snoring sound is generated byimpulses caused by rapid obstruction and opening of airways. Huang, etal., state the airway passage opening and closing occurs 50 times persecond during a snore. Huang, et al., utilize a spring-mass model (FIG.5) to illustrate oscillation of the soft palate in response to airflow(where the soft palate is the ball B of mass depending by a spring Sfrom a fixed anchor A).

[0040] Huang, et al., analogize the shortening of the soft palate SP inuvulopalatopharyngoplasty as effectively raising the critical air flowspeed at which soft palate flutter will occur. The shaded area SA inFIG. 3 shows the area of the trailing end TE of the soft palate SP to beremoved during this procedure. The alternative procedure proposed byHuang, et al., reduces the flexibility of the soft palate SP throughsurface scarring which is asserted as effecting the critical flow speed.The shaded area SA′ in FIG. 4 shows the area to be scarred by thisalternate procedure. In FIG. 4, dashed line L shows the demarcationbetween the soft and hard palates.

[0041] Using the spring-mass model of FIG. 5 as a convenient model ofthe soft palate SP, the present invention is directed to a surgicalimplant into the soft palate SP to alter the elements of the model andthereby alter the dynamic response of the soft palate SP to airflow. Theimplant can alter the mass of the model (the ball B of FIG. 5), thespring constant of the spring S, the dampening of the spring S or anycombination of these elements. Unlike the prior art surgical techniques,the implants that will be described are easy to insert in a smallincision resulting in reduced patient discomfort and are not exposed tothe interior of the mouth (such as the surface scarring of Huang, etal.) as a patient irritant. Also, as will be described, the degree ofdynamic remodeling can be fine tuned avoiding the need for excessiveanatomical modification and are reversible in the event of adverseconsequences.

[0042] FIGS. 6-7 illustrate a first embodiment of the present inventionwhere individual units 10 of mass (in the form of implantable modulardevices such as spheres or implants of other geometry) are imbedded inthe soft palate SP in close proximity to the trailing end TE. Withreference to the model of FIG. 5, the spheres add mass to themass-spring system thereby altering dynamic response to airflow andadding resistance to displacement and accelerating. The placement of theunits 10 of mass also alter the location of the soft palate's center ofmass further altering the model and dynamic response.

[0043] The embodiment of FIGS. 6-10 is tunable to a particular patientin that multiple modules 10 can be implanted (as illustrated in FIG. 7).This permits the surgeon to progressively increase the number ofimplanted modules 10 until the altered dynamic response is such thatsnoring inducing oscillation is abated at normal airflow. The individualmodules 10 may be placed into the soft palate SP through smallindividual incisions closed by sutures which is much less traumatic thanthe gross anatomical destruction of uvulopalatopharyngoplasty or thelarge surface area scarring proposed by Huang, et al.

[0044] Preferably, such modules 10 of mass are solid modules such asspheres of biocompatible material which are radiopaque (or radio-marked)and compatible with magnetic resonance imaging (MRI). Titanium is such amaterial. By way of non-limiting example, the modules 10 of mass may beabout 2-4 mm in diameter. In the case of pure, non-sintered titanium,each such sphere 10 would add 0.15-1.22 gm of mass to the trailing endTE of the soft palate SP and contribute to re-modeling the massdistribution of the soft palate SP. An example of an alternativematerial is any biocompatible ceramic.

[0045] As shown in FIG. 9, the spheres (labeled 10′ to distinguish fromthe version 10 of FIG. 8) may be sintered throughout or otherwiseprovided with tissue growth inducing material 12 on their outer surface.Such material may be a sintered outer layer or a coating or coveringsuch as a polyester fabric jacket. Such material permits and encouragestissue in-growth to secure the implant 10′ in place. Also, placement ofan implant 10 or 10′ will induce a fibrotic response acting to stiffenthe soft palate SP (and further alter the dynamic response andresistance to displacement and acceleration). A sintered or coatedsphere 10′ will enhance the fibrotic response and resulting stiffening.

[0046] While tissue in-growth and enhanced fibrotic response have thebenefits described above, such embodiments may make the implant 10′ moredifficult to remove in the event reversal of the procedure is desired.Therefore, as shown in FIG. 10 as an alternative, the spheres (labeled10″ to distinguish from the implants 10, 10′) may be coated with smoothcoating 14 (such as parylene or PTFE) to reduce fibrosis.

[0047] The embodiments of FIGS. 6-10 add to and relocate the mass of thespring-mass system of FIG. 5 to remodel the dynamic response. The amountof mass is selected to alter the dynamic response but not preclude thesoft palate SP being moved to close off nasal passages N duringswallowing. Through fibrotic response and incision healing, the spring Sof the model is stiffened.

[0048] In addition to modifying the mass profile of the spring-masssystem, the spring component S of FIG. 5 can be modified (alone or incombination with mass modification) to alter dynamic response. FIG.11-16 illustrate an implant 20 in the form of a flexible strip forplacement in the soft palate. The use of the term “strip” herein is notintended to be limited to long, narrow implants but can also includeplates or other geometries implanted to alter the dynamic model of thesoft palate SP. Elongated strips are presently anticipated as apreferred geometry to facilitate ease of implant.

[0049] The strip 20 has a transverse dimension less than a longitudinaldimension. By way of non-limiting example, the strip may have a lengthL_(S) of about 20-30 mm, a thickness T_(S) of about 2-4 mm and a widthW_(S) of 5-10 mm. As shown in FIG. 11, the strip 20 is embedded in thesoft palate SP with the longitudinal dimension L_(S) extending fromadjacent the hard palate HP toward the trailing end TE of the softpalate SP. As shown in FIG. 12, multiple strips 20 may be embedded inthe soft palate SP extending either straight rearward or angled to thesides while extending rearward. The strips 20 may be formed straight(FIG. 14) or pre-shaped (FIG. 15) to have a rest shape approximate tothe side-cross section shape of the soft palate in a relaxed state.

[0050] The strips 20 may be any flexible, biocompatible material and arepreferably radiopaque or radio-marked as well as MRI compatible. Thestrips 20 need not be elastic and having a material spring constantbiasing them to their original shape. Such strips 20 could simply beflexible, plastically deformable strips which are stiffer than the softpalate SP to reinforce the soft palate SP and assist the soft palate SPin resisting deflection due to airflow. Such stiffening of the softpalate SP stiffens and dampens the spring S in the spring-mass system ofFIG. 5 and alters the dynamic response of the soft palate SP. The strip20 may be a spring having a spring constant to further resist deflectionof the soft palate SP as well as urging the soft palate SP to therelaxed state of FIG. 5. The stiffness of the strip 20, a springconstant of the strip 20, and the number of strips 20, are selected toavoid preclusion of closure of the soft palate SP during swallowing.Examples of suitable materials include titanium and nitinol (awell-known nickel-titanium alloy). As with the examples of FIGS. 9 and10, the strips 20 may be provided with tissue in-growth surfaces or maybe coated as desired. Also, the strips may be structurally modified tocontrol their flexibility. In FIG. 16, the bottom 22 of the strip 20(facing the tongue after placement) is provided with transverse notches24 to enhance downward flexion of the strip 20 relative to upwardflexion of the strip 20 following placement.

[0051]FIG. 17 provides an alternative to the strips 20 of FIG. 13. InFIG. 17, the strip 20′ includes a housing 26 having an interior space 28with an access opening 25. The interior space 28 extends in thelongitudinal dimension of the housing 26. The strip 20′ further includesa longitudinal insert 32 sized to be passed through the access opening25 and into the space 28. By way of non-limiting example, the housing 26could be silicone rubber (with radio-markers, not shown, to indicateplacement) and the inserts 32 could be titanium rods or other flexiblemember. With the embodiment of FIG. 17, the housing 26 (without aninsert) may be embedded in the soft palate SP. The housing 26 actsindependently as a stiffening strip to add stiffness to the soft palateSP to alter the soft palate's dynamic response. In the event furtherstiffening or a spring action is desired, the implant 20′ can beselectively tuned to the patient's unique dynamic model by placing theinsert 32 into the space 28 at the time of initial surgery or during asubsequent procedure. The embodiment of FIG. 17, permits selection of aninsert 32 from a wide variety of materials and construction so that aninsert 32 of desired characteristics (e.g., stiffness and spring action)can be selected to be inserted in the space 28 and alter the dynamicresponse as desired. The embodiment of FIG. 17 also permits laterremoval of the insert 32 and replacement with a different insert 32 ofdifferent properties for post-surgery modification of the soft palate'sdynamic response.

[0052] The embodiment of FIG. 18 is similar to that of FIG. 17. Thehousing 26′ is provided with multiple, parallel-aligned interior spaces28′ and access openings 25′. In addition to the function and benefits ofthe embodiment of FIG. 17, the number of inserts 32 may be varied toalter and adjust the dynamic response of the soft palate SP.

[0053]FIG. 19 illustrates a still further embodiment of the stripimplant. In FIG. 19, the strip 20″′ is a bladder having a housing 26″ inthe form of a completely sealed envelope of flexible synthetic materialdefining an interior space 28″. The envelope 26″ is preferablyself-sealing following needle injection. Fluid is injected into thehousing 26″ (e.g., through hypodermic needle 40 injection) to stiffenthe strip 20″′. Addition of fluid further stiffens the strip 20″′ andfurther alters the dynamic response of the soft palate SP. Removal offluid increases the flexibility. Unlike the embodiments of FIG. 17(where inserts 32 are most effectively replaced post-operatively throughincision to alter flexibility), the embodiment of FIG. 19 permitsselectively varying flexibility of the soft palate SP through needleinjection. An alternative to FIG. 19 is to fill the space 28″ with aso-called phase change polymer and inject a stiffening agent into thespace 28″ to alter the flexibility of the polymer.

[0054] FIGS. 20-23 illustrate a still further embodiment of the presentinvention. In the foregoing embodiments, the spring-mass system of FIG.5 is altered by altering the mass of the soft palate SP or the springcharacteristics of the soft palate SP. The dynamic response can also bealtered by altering the force acting on the spring-mass system. Namely,the force acting on the soft palate SP is generated by airflow over thesurface of the soft palate. The soft palate acts as an airfoil whichgenerates lift in response to such airflow. By modifying thelongitudinal (i.e., anterior to posterior) cross-sectional geometry ofthe soft palate SP, the aerodynamic response and, accordingly, thedynamic response are altered.

[0055] In the embodiments of FIGS. 20-23, the implant 30 is insertedinto the soft palate SP through an incision. The implant 30 has an ovalshape to cause deformation of the geometry of the soft palate SP. Priorto implantation, the implant 30 is preferably formed as a flat oval(FIGS. 20 and 22) for ease of insertion. After implantation, the implant30 expands to an enlarged oval (FIG. 21 and 23). While such expansioncould be accomplished mechanically (i.e., through balloon expansion),the implant 30 is preferably formed as a shape-memory alloy (such asnitinol) which expands to the enlarged shape in response to the warmthof the body. In addition to changing the aerodynamics of the soft palateSP, the implant 30 can be constructed with a mass and stiffness asdesired to alter the spring and mass components of the spring-masssystem of FIG. 5.

[0056] The foregoing describes numerous embodiments of an invention foran implant for the soft palate to alter a dynamic response of the softpalate. The invention is much less traumatic than prior surgicaltreatments. Further, the invention permits use of reversible proceduresas well as procedures which can be selectively tuned both during surgeryand post-operatively. Having described the invention, alternatives andembodiments may occur to one of skill in the art. For example, thestrips of FIG. 13 may be encased coiled springs which may be tightenedto further stiffen the strips. Such strips may also be hinged segments.It is intended that such modifications and equivalents shall be includedwithin the scope of the following claims.

What is claimed is:
 1. A method for treating an airway condition of apatient where said airway condition is characterized by a dynamicresponse of a tissue of said airway to airflow, said method comprising:selecting an implant dimensioned so as to be implanted into said tissue,said implant having mechanical characteristics for said implant, atleast in combination with a fibrotic tissue response induced by saidimplant, to alter said dynamic response of said tissue withoutapplication of force external to said tissue; implanting said implantinto said tissue to alter said dynamic response.
 2. A method accordingto claim 1 comprising providing said implant to have a mass sufficientto alter said dynamic response following said implantation withoutsubstantially impairing a function of said tissue.
 3. A method accordingto claim 1 comprising providing said implant to dampen said dynamicresponse following said implantation without substantially impairing afunction of tissue.
 4. A method according to claim 1 comprisingproviding said implant to stiffen said tissue to alter said dynamicresponse following said implantation without substantially impairing afunction of said tissue.
 5. A method for treating an airway condition ofa patient where said airway condition is characterized by a dynamicresponse of a tissue of said airway to airflow, said method comprising:selecting an implant dimensioned so as to be implanted into said tissue,said implant having mechanical characteristics for said implant, atleast in combination with a fibrotic tissue response induced by saidimplant, to alter said dynamic response of said tissue to air flow pastsaid tissue without application of force external to said tissue, andsaid implant having a longitudinal dimension and a narrower transversedimension and said implant being flexible along said longitudinaldimension, said implant further dimensioned so as to not substantiallyincrease a bulk of said tissue following implantation of said implantinto said tissue; and implanting said implant within said tissue toalter said dynamic response.
 6. A method for treating an airwaycondition of a patient where said airway condition is characterized by adynamic response of a tissue of said airway to airflow, said methodcomprising: selecting an implant dimensioned so as to be implanted intosaid tissue, said implant having mechanical characteristics for saidimplant, at least in combination with a fibrotic tissue response inducedby said implant, to alter said dynamic response of said tissue to airflow past said tissue without application of force external to saidtissue, and said implant having a longitudinal dimension and a narrowertransverse dimension and said implant being flexible along saidlongitudinal dimension, and said implant having a stiffness selected tostiffen said tissue to alter said dynamic response following saidimplantation without substantially impairing a function of said tissue;implanting said implant within said tissue to alter said dynamicresponse.
 7. A method according to claim 1 wherein said airway conditionis snoring.
 8. A method according to claim 1 wherein said tissue is asoft palate.
 9. A method according to claim 5 wherein said airwaycondition is snoring.
 10. A method according to claim 5 wherein saidtissue is a soft palate.
 11. A method according to claim 6 wherein saidairway condition is snoring.
 12. A method according to claim 6 whereinsaid tissue is a soft palate.